D1224

I have a 1965 olds 98 with the 3spd auto, it’s a daily driver and I have this problem when staring off it sometimes shakes violently unless I drop it into second or it just won’t move like it’s in neutral. Any ideas? Any help is appreciated.

rocketraider

First thing I'd try is a fluid and filter change.

This car has what is known as a Switch-Pitch torque converter. If the throttle linkage is off adjustment it's possible the torque converter stator angle may not be switching angles at idle, though that usually shows as sluggish off-the-line acceleration and moving between D and S shouldn't affect it.

There are people here who are good at automatic transmission diagnosis. Hopefully they'll see this post.

matt69olds

Before doing anything, drop the pan. If there is a bunch of debris, chances are the trans is worn out. If all you see is a little clutch material, change the filter and refill.


To move forward, a 400 trans needs the forward clutch on, and for the low/reverse roller clutch to be engaged (holding) the roller clutch overruns (freewheels) in reverse. To get second gear, the intermediate clutch comes on, for 3rd the direct clutch comes on, everything else stays the same. If the forward clutch was slipping, I would expect being able to duplicate the concern in second gear and third gear , given enough throttle.

Next time it happens, put the shifter in low gear. That brings on the low/reverse band. Without get too technical, that prevents the roller clutch from overrunning. Basically, it positively locks the part the low roller clutch holds only in the forward gears. If putting the shifter in low gear stops the chattering, then I’d suspect the roller clutch is junk.

There is also a roller clutch in the torque converter, if that sprag is worn and chattering, it can also make the car feel funny. However, the converter has no clue what gear the trans is in. If there is no debris in the pan, and changing the fluid/filter does nothing, then it’s time to pull the trans for a autopsy. The converter should be replaced anytime the trans is overhauled.

oldcutlass

First I'd check the fluid level and make sure the color is a bright purplish pink color. If it's brown and smells burnt, your probably due for some transmission work.